We have not had any problems using our RBC debit cards in the U.S. For cash, we have found that the easiest to go Walmart, make your purchase, usually groceries and as in Canada, the debit machine asked if your want cash back, process as normal and collect your cash $100 max per transaction. The only limits we have found are what your bank has attached to your account, usually $500 per day.
Yes the debit card works at US bank ATMs, usually with a fee$$ that Walmart and other stores do not charge.
Our bank statement shows the US amount charged/debit plus the exchange rate of the day processed and the total against our account.
Last two times that we have crossed at Detroit, we were asked about cash, and when we told them about $40 US, ??. When I told him that we had access to our bank accounts through debit with cash back, he was satisfied and sent us on our way.
Beverley and Ken